Brandon Mobley drives to the basket during the second half of Seton Hall's win over Norfolk State. Photo: Anthony J. Causi

Brandon Jacobs had to learn it. Derrick Ward had to learn it. Ahmad Bradshaw had to learn it. All three eventually became 1,000-yard backs for the Giants but they didn’t get on the field until they learned the finer points of playing running back.

None of those three were high draft picks. Rookie David Wilson is a first-round pick and he’s having loads of trouble finding playing time.

“Just because you’re a first-round draft pick doesn’t mean you’re ready to play or they all would be great,’’ running backs coach Jerald Ingram said yesterday. “It’s about winning games, it’s not a popularity contest. It’s time for you to grow up and be a man now and see what you can do with the whole ball of wax. Until [Wilson] proves that, it’s hard to stick him out there and feel comfortable.’’

Wilson has just 18 rushing attempts in the Giants’ first 10 games as he struggles to learn in the ins and outs of pass protection and blitz pickup.

“Yeah, he is explosive, but at what cost is he explosive?’’ Ingram asked. “Is he explosive at the cost of not being able to protect well, not being able to know his job well, not being a pro?’’

* Rookie DT Markus Kuhn came out of the 31-13 loss to the Bengals with a torn right ACL, ending his season. The seventh-round pick, a native of Germany, was part of the defensive line rotation and playing better than the Giants thought he would.

“He plays a big role,” defensive coordinator Perry Fewell said. “Markus Kuhn’s done a really nice job. Nobody really talks about him and that’s good, because he just comes in and does his job.’’

Kuhn called the injury “definitely a bummer.’’

* Bradshaw will undergo a battery of tests before he leaves for the bye week. Bradshaw has been dealing with chronic foot issues. He also missed a game earlier this season with a neck injury and he will have that checked out as well. … Eli Manning laughed when asked what he thought about coach Tom Coughlin deferring until the second half after the Giants won the toss. “That was one of the few times and obviously it didn’t really work all that well, so hopefully it might be the last,’’ Manning said. … The offensive line has taken a step back the past few games, since David Diehl reclaimed his starting right tackle job from Sean Locklear. “You would love to say it’s this one thing or one person or one aspect, but it doesn’t work out that way,’’ offensive coordinator Kevin Gilbride said when asked if Diehl has struggled. “Believe me when I tell you this, it’s all of us.

The 56-yard touchdown pass to a wide-open A.J. Green early in the first quarter? Fewell said safety Stevie Brown should have been over the top and blew the coverage, which is why Green ran free after cornerback Corey Webster didn’t pursue him down the field. “He played his assignment,” Fewell said of Webster, “but you would expect a veteran like that to say, ‘He’s not there,’ and realize he wasn’t there, and to keep running and continue on the play.” Fewell called it “two mistakes on one play.’’